Bowhead Whale and Mutated Whale: How to Fish Boss Guide

Updated 2026-09-02 · Steam How to Fish

The How to Fish Bowhead Whale is the Volcano Island boss you summon with a Fish Bucket after handing five creatures to the hazmat-suit scientist, and the Mutated Bowhead Whale is the final boss, spawned by carrying the dead whale up the volcano path and throwing it into the crater. Both share a two-attack pattern, a surface charge and a leap that stomps one player, and both come down to one answer: a fully attachment-equipped assault rifle plus a stack of lava-cooked food. The mutated version adds lava pools, meteorite fire and a far more aggressive second phase. Every strategy detail below is player-tested, from Steam Community guides rather than the developers.

Where the whale bosses are

Volcano Island is the fifth and last island of the main route, and the whale pair closes out the run. The small How to Fish Fandom wiki describes the route as five island stages and ten boss encounters ending with the Mutated Bowhead Whale. See bosses for the order and albatross for the island 4 fight that gates entry. Patch 1.0.4 (21 August 2026) made "the intended path up to the final island easier to see".

Summoning the Bowhead Whale

The Bowhead Whale is not caught on a normal lure. Per the community guide "Bait & Fish Guide", its bait is the Fish Bucket, and the Mutated Bowhead Whale's "bait" is the Bowhead Whale corpse itself.

Step	What to do	Notes
1	Get five creatures, any species	Players report dynamite in the water is fastest
2	Hand them to the scientist in the hazmat suit	He gives back the whale bait, the Fish Bucket
3	Cast the Fish Bucket and reel the whale in	The fight starts on the shore
4	Carry the whale body up the volcano path	Slow climb, do it before your food runs out
5	Throw the whale into the volcano's mouth	The Mutated Bowhead Whale spawns above you

Guide authors disagree on which whale the "Deadliest Catch" achievement tracks: one calls it the regular whale, another the lava whale, with the hazmat scientist as the "military" the achievement text names. Neither reading is confirmed in patch notes, so treat it as player-reported and check achievements.

Bowhead Whale vs Mutated Bowhead Whale

Feature	Bowhead Whale	Mutated Bowhead Whale
Where	Volcano Island shoreline	Above the volcano crater
How to start	Fish Bucket from the scientist	Throw the whale corpse into the crater
Charge attack	Yes, lunges along the surface	Yes, plus rolling
Aerial stomp	Yes, targets one player	Yes, and far more often in phase 2
Ground hazard	None	Lava pools left behind, plus lava meteorites across the arena
Phase 2	Not reported	Constantly stomping, repeatedly launching into the sky to fire down
Drop	Body, used to spawn the final boss	Tail, traded to the scientist for the RHIB keys
Exact health	Not published	Not published

Neither whale's health value appears in any developer post. Guides only call it a "massive health pool", which is why the recommended weapon is the game's strongest.

Assault rifle strategy

The community guide "How to Fish: Complete Boss & Weapon Strategy Guide" rates the assault rifle as a costly buy that endgame bosses with huge health pools still require, and its advice here is to hold maximum range on the shoreline, tap-fire to control recoil, and aim for weak spots. Another guide puts a fully-attachment rifle with maximum ammo capacity at roughly $85,000, which is why players farm island 5 fish before pulling the bait.

Dodging is split by attack type, both player-tested:

Charge. Circle the boss and keep firing. It closes in small lunges rather than one long dash, so a steady orbit keeps you ahead of it.
Aerial stomp. Watch which player it locks on to while airborne. That player sprints out of the landing zone, everyone else keeps shooting. Solo, just move as soon as it leaves the water.
Mutated only. Treat lava pools as a third attack. The burn does heavy damage over time, and the phase 2 stomp cadence leaves little room to stand still.

Speedrunners max an SMG instead, because it is far cheaper and the run cannot spare the fishing time for a rifle: a time-optimised compromise, not the safest option. See bean-achievement and weapons for costs and attachment order.

Healing: lava cooking is the real prep

Volcano Island's lava cooks food at a reported flat 1.5x value with no timing risk, so it doubles as a free grill. Two player-tested healing sources matter:

Gastropods (players also call them footsnails) spawn near the lava sources. Fried in lava, guides say one restores almost all of your health.
Dynamite-caught fish cooked by the lava streams. Build a large pile before you summon the first whale, then restock between the two fights.

The consistent advice is that you cannot over-prepare for the ending: after the first whale dies, hunt more snails, dynamite more fish, cook everything, and only then throw the corpse into the crater. Species and values are on the fish page.

Difficulty settings change the fight

Patch 1.0.9 (24 August 2026) added a difficulty option in the main menu and in-game. Developer-confirmed, and it applies to all creatures, bosses included.

Difficulty	Creature health	Creature damage
Easy	25% less	50% less
Default	Unchanged from launch	Unchanged from launch
Hard	25% more	25% more

Patch 1.0.4 also listed a plain "Nerfed Whale" balance change, so any video recorded on 1.0.0 to 1.0.3 shows a tougher whale than today's. The same patch fixed the bare-hands final boss achievement so it unlocks for everyone in the lobby.

Mods that make the fight readable

A few Thunderstore mods help against a boss whose health is never shown as a number. These are read-only HUD mods, not combat automation.

Mod	Author	Downloads	What it does
BossHP	evansvl	11,708	Shows the exact synchronized boss HP next to the native bar
BossTimer	evansvl	8,649	Native-style HUD showing time remaining before the active boss leaves
FishHP	evansvl	14,346	Stacked HP bars for living non-boss creatures you damage, with configurable colour

BossHP is the practical one for the bare-hands achievement, where you shoot the mutated whale down to a sliver and punch it out. All three depend on BepInExPack. Aimbot and cheat-menu mods for bosses also exist on Thunderstore, and this site does not cover them.

After the final boss

The Mutated Bowhead Whale drops a tail. Take it to the scientist, get the RHIB keys, start the boat, and the ending plays. Guides note the bookend: the island 1 spider crab drops a shell that buys the first boat keys, the last boss a tail that buys the last. After the credits you restart on island 1 still holding everything you own, with all five islands open, and that is where most of the remaining 28 achievements get cleaned up.

Sources and last check

Checked 2 September 2026. Developer facts come from official Steam news posts: patch 1.0.4 of 21 August 2026 ("Nerfed Whale", clearer path to the final island, bare-hands boss achievement fix) and patch 1.0.9 of 24 August 2026 (the easy and hard difficulty modes).

Attack patterns, the Fish Bucket bait chain, the roughly $85,000 rifle setup, lava-cooked gastropods as healing, the 1.5x lava cooking rate, the SMG speedrun alternative and the tail-for-RHIB-keys ending are all player-reported, from the Steam Community guides "How to Fish - All 28 Achievements + Post-Game Route", "How to achieve / The Ultimate Guide to Unlocking All Achievements", "How to Fish: Complete Boss & Weapon Strategy Guide" (30 August 2026) and the "Bait & Fish Guide". Where those guides conflict over which whale Deadliest Catch counts, both readings are given above. Mod download counts are a Thunderstore API snapshot from 2 September 2026 and will drift.